This invention relates to a printed circuit board base material which has a low dielectric constant, possesses desirable strength properties and transmits electric signals at high speeds.
For the purpose of permitting production of printed circuits of high operating speed which are suitable for the recently developed super-highspeed elements such as gallium arsenide IC's, development of a material having a low dielectric constant for printed circuit boards is indispensable to preclude delay in propagation time. Several efforts have been devoted to date to the development of such materials.
As such materials, polyimide resin and polyester resin have been used for impartation of flexibility. For materials requiring rigidity, molded articles of epoxy resin, phenolic resin, and polyimide resin reinforced with glass fibers, fabric, or paper have been used.
The conventional printed circuit boards such as the polyimide resin and the polyester resin mentioned above, glass/epoxy board, and paper-phenol board have dielectric constants not lower than 3.5 (at 1 MHz) and generally falling on the order of 4.0 to 5.0. Thus, they are not capable of meeting the aforementioned requirement that devices of high operating speed should be developed so as to permit full utilization of the recently developed ultra-high-speed elements.